Transition metals (Chem only) – GCSE Chemistry exam questions with mark scheme

1Grade 1–3FoundationTriple only3 marks

(a) Which of these elements is a transition metal?

Tick (✓) one box.

☐ caesium ☐ calcium ☐ carbon ☐ cobalt [1]

(b) Transition metals have different properties from Group 1 metals.

Which two statements about transition metals are correct when they are compared with Group 1 metals?

Tick (✓) two boxes.

☐ They are less dense.
☐ They have higher melting points.
☐ They react more vigorously with cold water.
☐ They are harder and stronger.
☐ They only form ions with a 1+ charge.

[2]

(a) cobalt(1)
(b) they have higher melting points(1)
(b) they are harder and stronger if more than two boxes ticked, deduct one mark for each extra tick (minimum 0)(1)
Answer: (a) cobalt (b) higher melting points; harder and stronger
Examiner tip: Caesium and calcium both start with “c” and are metals — but they are in Groups 1 and 2. Look for the block in the middle of the periodic table.

2Grade 4–5Triple only4 marks

The bar chart shows the melting points of some Group 1 metals and some transition metals.

(a) Describe how the melting points of the transition metals compare with the melting points of the Group 1 metals. [1]

(b) Use the bar chart to estimate the difference between the melting point of chromium and the melting point of potassium. [1]

A student says:

“Every transition metal has a higher melting point than every Group 1 metal.”

Use the information to explain whether the student is correct. [2]

(a) transition metals have (much) higher melting points allow converse; ignore references to individual metals only(1)
(b) 1800–1900 (°C) (1907 − 63 = 1844)(1)
(c) the student is not correct: mercury is a transition metal with a lower melting point than (all) the Group 1 metals / mercury is an exception allow mercury is a liquid at room temperature (so its melting point is lower than any Group 1 metal); ignore 'not correct' with no reason(1)
(c) use of data: −39 °C is lower than the melting point of potassium (about 60 °C) allow comparison with sodium (about 100 °C) or lithium (about 180 °C) using values read from the chart; do not award this mark without a reference to mercury(1)
Answer: (a) much higher (b) about 1840 °C (allow 1800–1900) (c) not correct: mercury is a transition metal, and its melting point (−39 °C) is lower than potassium’s (about 60 °C)
Examiner tip: In (c) you must use the data: quote mercury’s value against a Group 1 value — “mercury is a liquid” on its own does not prove the claim wrong.

3Grade 4–5Triple only4 marks

The table shows some ions.

Positive ions	Negative ions
Cu⁺ Cu²⁺	O²⁻
Fe²⁺ Fe³⁺	Cl⁻

(a) Give the formula of copper(I) oxide. [1]

(b) Give the formula of copper(II) chloride. [1]

Give the charge on the iron ion in FeCl₃. [1]

(d) Sodium only forms Na⁺ ions.

Give the property of transition metals shown by copper and iron in the table that sodium does not show. [1]

(a) Cu₂O do not accept CU₂O or Cu2O written as Cu²O(1)
(b) CuCl₂ do not accept CuCl² or CuCL₂(1)
(c) 3+ allow +3 / Fe³⁺; do not accept 3 or 3− (1)
(d) (they) form ions with different charges allow form more than one ion / have variable charges; ignore “form ions” alone; ignore form coloured compounds(1)
Answer: (a) Cu₂O (b) CuCl₂ (c) 3+ (d) form ions with different charges
Examiner tip: The Roman numeral is the charge on the metal ion — balance it with the negative ion: two Cu⁺ are needed for one O²⁻, so Cu₂O, not CuO.

4Grade 1–3FoundationTriple only3 marks

A student dissolved some metal compounds in water. The table shows the colour of each solution.

Compound	Colour of solution
copper(II) sulfate	blue
nickel(II) sulfate	green
potassium sulfate	colourless
cobalt(II) chloride	pink
sodium chloride	colourless

(a) Give one property of transition metal compounds shown by the table. [1]

(b) The student is given a blue solution of one of the compounds in the table.

Which compound is in the blue solution? [1]

Suggest why. [1]

(a) (they are / form) coloured (compounds) allow their solutions are coloured; ignore named colours alone(1)
(b) copper(II) sulfate allow CuSO₄; allow copper sulfate(1)
(c) to give the glass colour / to make the glass coloured ignore “to make it look nice” without reference to colour(1)
Answer: (a) coloured compounds (b) copper(II) sulfate (c) to colour the glass
Examiner tip: Answer “coloured” for (a) — writing just “blue” or “green” describes one compound, not the property.

5Grade 6–7Triple only7 marks

Hydrogen peroxide decomposes to form water and oxygen.

A student compared two transition metal compounds as catalysts for this reaction. She used the same volume and concentration of hydrogen peroxide and 0.50 g of catalyst each time.

The graph shows her results.

(a) Which compound was the more effective catalyst? Give a reason for your answer. [1]

(b) Calculate the mean rate of reaction with manganese(IV) oxide in the first 20 s.

Give the unit. [2]

Explain what this result shows. [2]

(d) The formula of manganese(IV) oxide is MnO₂. Manganese also forms the compound MnCl₂.

Give the charge on the manganese ion in each compound. [2]

(a) manganese(IV) oxide and the line is steeper / it produced oxygen faster / it reached 60 cm³ first allow MnO₂; do not accept “produced more oxygen”(1)
(b) 45 ÷ 20 = 2.25 allow 2.2 or 2.3; allow reading of 44–46 cm³ correctly divided by 20(1)
(b) cm³/s allow cm³ s⁻¹; unit mark independent(1)
(c) (the mass is unchanged so) manganese(IV) oxide is not used up (in the reaction)(1)
(c) so it is a catalyst / it can be used again allow it does not appear in the overall equation; ignore “it speeds up the reaction” alone(1)
(d) MnO₂: 4+ allow +4 / Mn⁴⁺(1)
(d) MnCl₂: 2+ allow +2 / Mn²⁺(1)
Answer: (a) manganese(IV) oxide – steeper line (b) 2.25 cm³/s (c) mass unchanged → not used up, so it is a catalyst (d) 4+ and 2+
Examiner tip: In (a) both catalysts eventually give the same volume of oxygen — the evidence is the gradient, not the final volume.

6Grade 6–7HigherTriple only5 marks

Iron(II) chloride solution reacts with chlorine to form iron(III) chloride.

(a) Balance the equation for the reaction.

…… FeCl₂ + Cl₂ → …… FeCl₃ [1]

(b) Iron(II) chloride solution is pale green. Iron(III) chloride solution is yellow-brown.

Give the colour change you would see during the reaction. [1]

Fe²⁺ → Fe³⁺ + …… [1]

(d) Explain why the iron(II) ions are oxidised in this reaction. [1]

(e) Write a half equation for the change to chlorine in this reaction. [1]

(a) 2 (FeCl₂) + Cl₂ → 2 (FeCl₃) both needed(1)
(b) (pale) green to yellow-brown allow green to yellow / orange / brown; must be in the correct order(1)
(c) e⁻ allow e; allow 1e⁻(1)
(d) (each iron(II) ion) loses an electron allow loses electrons; do not accept gains electrons or loses oxygen / gains chlorine(1)
(e) Cl₂ + 2e⁻ → 2Cl⁻ allow Cl₂ → 2Cl⁻ − 2e⁻; ignore state symbols; allow multiples(1)
Answer: (a) 2FeCl₂ + Cl₂ → 2FeCl₃ (b) pale green → yellow-brown (c) e⁻ (d) Fe²⁺ loses an electron (e) Cl₂ + 2e⁻ → 2Cl⁻
Examiner tip: OIL RIG: the charge going up from 2+ to 3+ means an electron was lost — students who write “gains a positive charge” or “gains electrons” lose (d).

7Grade 4–5Triple only4 marks

Copper is a transition metal. Sodium is a Group 1 metal.

Copper is used to make hot water pipes in houses.

Explain two reasons why sodium could not be used to make hot water pipes. [4]

sodium reacts (vigorously) with water / sodium is (very) reactive allow copper does not react with water(1)
so the pipe would be used up / would produce hydrogen (which is flammable) / would produce sodium hydroxide (an alkali) in the water allow so the pipe would dissolve / would be destroyed / would leak(1)
sodium has a low melting point (98 °C) / sodium is soft / sodium is weak allow copper has a high melting point / is strong / is hard(1)
so the pipe would melt (close to boiling water temperature) / would bend / lose its shape / break linked consequence must match the property given(1)
Answer: Sodium reacts violently with water (pipe destroyed, hydrogen produced); sodium is soft with a low melting point (pipe would bend or soften/melt in hot water).
Examiner tip: Each reason is two marks: the property and what it would do to the pipe. “Sodium is reactive” alone is only half a reason.

8Grade 8–9HigherTriple only5 marks

A and B are two different oxides of iron.

A student heated 5.60 g of iron in oxygen until it had all reacted. The mass of oxide A formed was 8.00 g.

(a) Determine the formula of oxide A. You must show your working.

Relative atomic masses ($A_r$): O = 16 Fe = 56 [3]

(b) Under different conditions, 5.60 g of iron formed 7.20 g of oxide B.

Determine the formula of oxide B. [1]

Give the charges on the iron ions in oxide A and oxide B. [1]

(a) mass of oxygen = 8.00 − 5.60 = 2.40 (g)(1)
(a) moles: Fe = 5.60 ÷ 56 = 0.100 and O = 2.40 ÷ 16 = 0.150 allow ratio 1 : 1.5(1)
(a) Fe₂O₃ correct answer with no working scores 1 mark only(1)
(b) FeO (0.100 mol Fe : 1.60 ÷ 16 = 0.100 mol O)(1)
(c) A: 3+ and B: 2+ allow Fe³⁺ and Fe²⁺; allow ecf from formulae in (a) and (b)(1)
Answer: (a) Fe₂O₃ (b) FeO (c) A: Fe³⁺, B: Fe²⁺
Examiner tip: Find the mass of oxygen first (product − iron). Dividing 8.00 g of oxide by 16 is the most common way to lose every mark here.

9Grade 6–7Triple only6 marks

Chromium is a transition metal. Potassium is a Group 1 metal.

Compare the physical and chemical properties of chromium and potassium.

You should refer to their compounds in your answer. [6]

Physical: chromium has a much higher melting point (and boiling point) than potassium(1)
chromium has a much higher density than potassium / potassium is less dense than water (floats)(1)
chromium is harder / stronger than potassium; potassium is soft (can be cut with a knife)(1)
both are metals: both are good conductors of electricity and heat / both are shiny when freshly cut(1)
Chemical: potassium reacts vigorously with cold water (fizzing, melts, lilac flame); chromium does not react (noticeably) with cold water(1)
potassium tarnishes quickly in air / reacts quickly with oxygen; chromium reacts very slowly / is resistant to corrosion(1)
potassium reacts vigorously with halogens (e.g. chlorine); chromium reacts much less readily(1)
overall chromium is much less reactive than potassium(1)
Compounds / ions: potassium forms only K⁺ ions; chromium forms ions with different charges (e.g. Cr²⁺ and Cr³⁺)(1)
chromium compounds are coloured (e.g. green, orange); potassium compounds are white / colourless (solutions)(1)
chromium (or its compounds) are useful catalysts – a typical property of transition metals that Group 1 metals do not show(1)

Level	Marks	What it looks like
Level 3	5–6	Detailed, direct comparisons of both physical and chemical properties, including at least one property of the compounds (ion charges, colour or catalysis). Comparisons are clear and linked to the two named metals throughout.
Level 2	3–4	Several relevant comparisons covering physical and chemical properties, though some points describe only one metal or the compounds are not mentioned.
Level 1	1–2	Simple statements about one or two properties, which may describe only one metal or may not be comparative.
No relevant content	0	No relevant content.

Answer: Cr: high melting point and density, hard and strong, much less reactive with water, oxygen and halogens, forms ions with different charges, coloured compounds, catalysts. K: low melting point and density, soft, reacts vigorously with water/oxygen/halogens, only K⁺, white compounds.
Examiner tip: “Compare” needs both metals in every point (chromium has a higher melting point than potassium). Two separate lists describing each metal will not reach Level 3.

10Grade 6–7Triple only4 marks

The table shows information about four metals, A, B, C and D.

Metal	Melting point in °C	Density in g/cm³	Reaction with cold water	Colour of chloride solution
A	98	0.97	fizzes rapidly	colourless
B	1495	8.90	no reaction	pink
C	650	1.74	very slow	colourless
D	39	1.53	explodes	colourless

(a) Which two metals are in Group 1? [1]

(b) Which metal is a transition metal?

Give two reasons for your answer, using data from the table. [3]

(a) A and D both needed(1)
(b) B(1)
(b) any two from:
- (highest) melting point / 1495 °C is much higher than the others / than A and D
- (highest) density / 8.90 g/cm³ is much higher than the others
- no reaction with (cold) water so it is the least reactive
- its chloride solution is coloured / pink (the others are colourless)
reasons must be comparative or quote data; ignore “it is a metal”
(1)
(b) second reason from the list above(1)
Answer: (a) A and D (b) B: highest melting point and density, does not react with cold water, its chloride solution is coloured (pink)
Examiner tip: Metal C has a fairly high melting point but a colourless chloride solution and a low density — check every column before deciding, and quote the numbers.

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